As a large aperture standard lens used for a photograph camera and video camera, many Gauss lenses, in which refractive power is substantially symmetric with respect to an aperture stop provided between the lenses, have been proposed (e.g. see Patent Document 1).
Conventional lenses, however, are not sufficiently downsized, and when such a lens is used in a camera, it is difficult for a user to hold the camera, and image blur occurs and image quality drops during exposure, because of the subtle blur of the camera generated when capturing an image (e.g. blur of camera generated when the user presses a release button).
A known method to solve this problem is combining a detection system for detecting camera blur, a computing system for controlling the shift lens group according to a value which is output by the detection system, and a drive system for shifting the shift lens group as an optical system that can shift images in the image-capturing lens, and correcting the image blur by driving the shift lens group so as to compensate for image blur due to camera blur.